A device for detecting battery abnormality, a battery system, and a terminal device are provided. The device includes a voltage-sudden-change detecting circuit, a current detecting circuit, and an abnormality detecting unit. The voltage-sudden-change detecting circuit is configured to detect whether a sudden change in voltage has occurred to a battery and output a sudden-change signal when the sudden change in voltage has occurred. The current detecting circuit is configured to detect a consumption current of the battery and output a small-current signal when the consumption current of the battery is smaller than a preset current threshold. The abnormality detecting unit is coupled with the voltage-sudden-change detecting circuit and the current detecting circuit, and configured to determine that the battery is abnormal upon reception of the sudden-change signal and the small-current signal, store state information on battery abnormality, and send the state information to a controller of a terminal device.